1. Field of the Invention
The present invention is related to the field of compensating for color vision anomalies of humans, and more specifically to real time video systems that adjust the color of the displayed images so as to present more color contrast within the range of perception of viewers suffering from color vision deficiencies.
2. Description of the Related Art
Color is used increasingly to encode visual information. A comprehensive description is found in a book titled Digital Color Management, Encoding Solutions, by Giorgianni and Madden, Addison Wesley, 1998. The book describes standards for representations of color in color space, such as those promulgated by CIE (Commission Internationale de 1′ Éclairage) in various coordinate systems (-LUV, -XYZ, -LAB, etc.).
It is well documented that, as compared to a healthy majority, a fraction of the population suffers from color vision deficiencies. These people are more commonly called color blind. Such deficiencies do not permit them, when viewing color images, to detect certain colors or discern color contrasts.
Color blindness is discussed in an article titled “Color displays for the color blind”, The Fifth Color Imaging Conference, pp. 17–22, by Jan Walraven and Johan W. Alferdinck, that is incorporated herein by reference. Importantly, color blindness is characterized in terms of a diagram that is reproduced herein as FIG. 1.
FIG. 1 is a chromaticity diagram in CIE-XYZ color space. This diagram appears in the art frequently in color. The range (gamut) seen by most people is within an RGB triangle, defined by corner points R (red), G (green), and B (blue). The colors are digitally distributed within this triangle which has an area N.
The diagram also includes results of simulations of the perceptual constraints of anomalous color vision. As such, the diagram characterizes the visions of a protanomalous and of a deuteranomalous observer as triangles having respective areas P and D. The colorblind do not see color or color contrast outside their triangle.
The vision triangles of the color blind are smaller than, and substantially contained within the RGB triangle of a healthy person. The diagram thus properly presents colorblindness as a deficiency in range (gamut) of perception of color compared to the range of most people.
It is desirable to generate real time video for digital TV and related applications, that is adjusted for colorblind people.
Little work has been done in this direction. U.S. Pat. No. 5,589,898 addresses color compensating for computer screens. However, even that patent admits that its own disclosure is not applicable to real time video, such as TV screens and video screens (column 7, lines 2–7).